Question

The organisms that are prokaryotic and possess specialized structures called heterocysts to aid in fixing atmospheric nitrogen are Dinoflagellates cyanobacteria Algae Archaea Penicillium Question 31 The organisms that have silicious cell walls and can produce domoic toxins Diatoms Cyanobacteria Dinoflagellates Spirogyra Chlamydomonas

Answer 1

The dinoflagellates are protists living in both fresh and marine aquatic habitats. They make up large part of phytoplankton. They are unicellular with two dissimilar flagella. Some members are even bioluminiscent. Algae are photosynthetic protists and green algae such as charaophytes later evolved into land plants. The Archaea include extremophiles that live in high temperatures, pH and salt concentrations. The Penicillium is a mold and belong to fungi and it produces an antibiotic called penicillin. The cyanobacteria are also known as blue green algae. These are filamentous and prokaryotic. The cyanobacteria contain specialized structures called heterocysts that enable them to fix the atmospheric nitrogen. Therefore, the option 2 is correct.

31.

The domoic toxin is Domoic acid (DA) or a kainic acid-type neurotoxin. It is predominantly produced by certain type of diatoms. The diatoms are protists and phytoplankton. They have cell wall made up of silica and is called fustule with two halves, the epitheca and hypotheca. The domoic toxin produced by diatoms is accumulated in shell fish causing potential reaction in humans and marine animals. Therefore, the option 1 is correct.